CHAPTER 1

Soils and Mulches

Learning about your soil is the first step to a healthy and productive garden, and it’s a lifelong journey. The soil in your yard may be different than the soil from a prior home. It can be quite different from your neighbor’s land. And it can even differ around your property.

While it may seem like the best way to start the gardening journey is to haul in a load of brand spanking new soil and start fresh, that strategy can be fraught with challenges. Bulk topsoil or garden soil can come from a variety of different sources and can contain undesirable things, such as pesticides, herbicides, and plastics. Adding poor quality soil to a garden can cause damage that could take many years to repair.

Even if you do get excellent quality topsoil and the first year of gardening is wildly productive, those easily accessed nutrients will soon be depleted. After that, the new soil will need to be amended annually until it becomes rich with the organic matter and microbes that make up living soil. A much less expensive and productive way to is to start by amending the soil you have. But before you can do that, you need to assess it.

Take some time to meet your soil. Learn about its natural structure, pH, and health. In this chapter, I’ll share some simple home tests for evaluating your soil as a foundation for the garden alchemy you will use to grow a healthy, regenerative, and thriving garden. Learning to work with what you have is a skill that will save you time, energy, and money in the long run.

At-Home Soil Testing

A soil test is an important first step in getting to know the soil you are working with. Basic home tests can give you a better understanding of the soil composition and pH, which will serve as a basis for the recipes in this book.

With just a bit of information about your soil, you will begin your relationship with the land, learning about what works and what doesn’t work for your space. Some of the plants you grow will effortlessly take root, while others may struggle despite your best efforts. Learning to work with your soil as opposed to fighting its nature will bring the gardener in sync with the garden.

While this strategy works well for many home gardeners, if plant problems are persistent and your efforts are not resolving the issues, lab testing provides a detailed qualitative assessment of your soil, including nutrients, toxins, and microbes.

Simple Squeeze Test

This quick and simple test can be done right in the garden with minimal time or disruption. Take a handful of soil from the garden and squeeze it into a ball. Poke it with your finger and observe the results:

• If it sticks together, it’s clay.

• If it falls apart somewhat, it’s loam.

• If it falls apart completely, it’s sand.

How to Collect a Soil Sample

To collect a soil sample, dig down 3 to 4 inches (7.5 to 10 cm) with a trowel and scoop soil into a bowl. Take three to five samples from different parts of the garden and mix them together. Do not to touch the sample with your hands to avoid altering the pH.

Soil Composition Test in a Mason Jar

Soil is made up of sand, silt, and clay. The ideal balance of these particles for garden soil is called “loam.” It is suitable for growing most plants as it has a great balance of air pockets, moisture and nutrient retention, and drainage.

Test It!

Loam is made up of 40 percent sand, 40 percent silt, and 20 percent clay.

• Sand makes up the largest soil particles (between 0.05 to 2 mm in diameter)

• Silt makes up the intermediate size soil particles (between 0.002 to 0.05 mm in diameter)

• Clay makes up the smallest soil particles (smaller than 0.002 mm in diameter)

To determine the mix of soil you have in your garden, fill a 1-quart (1 liter) Mason jar one-third full with garden soil. Fill the rest of the jar with water and close the lid tightly. Shake the jar well. Let the contents settle overnight. In the morning, there will be up to four visible layers from bottom to top: sand, silt, clay, and water.

Results

Measure the percentages of sand, silt, and clay to learn your garden soil’s composition. Additionally, the clarity of the water sheds light on soil composition.

• If the water is clear, the soil is primarily free-draining sand.

• If the water is murky with soil suspended, it is loam.

• If the water is murky with visible sediment around the jar, it is mostly clay.

Soil pH Tests

In chemistry, pH measures how acidic or alkaline soil is based on a scale from 0 to 14. A pH of 7 is considered neutral, while values of 0 to 7 indicate acidity and, 7 to 14 indicate alkalinity. Soil pH is typically between 4.5 to 9. Most plants thrive in neutral soil—with a pH near 6.5 to 7—with a few exceptions. Acid-loving plants such as rhododendrons and blueberries prefer a lower pH between 4.5 to 5.5, while others such as asparagus and sweet pea can tolerate a pH slightly above 7. Some plants can tolerate a range of soil pH.

Vinegar and Baking Soda pH Test

This simple test for soil pH will tell you if you have alkaline, acidic, or neutral soil using household vinegar and baking soda. Vinegar is acidic and sodium bicarbonate (baking soda) is alkaline. When they are mixed together, they fizz. With two samples of soil from the same place in your garden, adding these ingredients will help to determine your soil’s pH type.

Materials

2 small bowls

4 tablespoons soil

Distilled water (do not use tap water as distilled water has a neutral pH)

White vinegar

Sodium bicarbonate

Make It!

Add 2 tablespoons (30 ml) soil to a small bowl and mix with 1 tablespoon (15 ml) distilled water. Add 1 tablespoon (15 ml) white vinegar and stir. If the mixture fizzes, you have alkaline soil.

Add 2 tablespoons (30 ml) soil from the same sample to a small bowl and mix with 1 tablespoon (15 ml) distilled water. Add 1 tablespoon (15 ml) baking soda and stir. If the mixture fizzes, you have acidic soil. If it does not fizz for either test, you have neutral soil.

Cabbage Water pH Test

Make a pH indicator solution using red cabbage water in this colorful home test. Water-soluble pigments in cabbage—known as anthocyanins—turn pink to red when mixed with acidic soil, greenish yellow when mixed with alkaline soil, and bluish purple when mixed with neutral soil.

Materials

Saucepan

3 cups (710 ml) distilled water

1 cup (235 ml) finely chopped red cabbage

2 Mason jars

Soil samples

Test It!

1. Bring the distilled water and cabbage to a boil in the saucepan; simmer for 10 minutes. Allow the cabbage water to cool.

2. Add 1/2 cup (120 ml) of the cabbage water to each Mason jar and stir in 1 tablespoon (15 ml) garden soil. Let the samples sit for thirty minutes before reading the color.

DIY Soil pH Test Kits

There are plenty of soil test kits that you can buy to test soil pH, from electronic meters to paper strips. Each test has its own set of unique instructions and some can also measure sunlight, soil fertility, and moisture levels. The simplest and most economical option is all that is needed at home. Paper pH litmus tests can be purchased inexpensively in books or rolls offering hundreds of tests.

Test It!

1. To use a pH litmus test strip, mix a soil sample with distilled water for 30 seconds.

2. Touch the tip of the test paper to the top of the muddy mixture and hold it in place for one minute.

3. The water will be wicked up by the paper, and the pH reading can be taken from the point closest to the tip that is not covered in mud.

Change Hydrangea Bloom Colors

Hydrangea varieties such as Hydrangea macrophylla and H. serrata can range in color from pink to blue, with every shade of fuchsia, plum, and periwinkle in between. The blooms can change color based on the amount of aluminum the plants absorb from the soil, which depends on soil pH. High levels of aluminum in the soil plus an acidic soil pH will generate the coveted bright blue to purple flowers, while less aluminum in the soil and/or alkaline soil will create a variation of pink blooms. Not all hydrangea species change color, however. White ones do not change, and some varieties are bred for a specific color palette.

Materials

For blue flowers: 1/2 cup (120 ml) sulfur per 10 square feet (1 square meter).

For pink flowers: 1 cup (235 ml) garden lime per 10 square feet (1 square meter).

Make It!

1. Add sulfur or garden lime to alter the pH.

2. Repeat every 3 months for blue flowers and every 2 months for pink flowers.

Changing the pH of your soil is a gradual process that can take up to a year for the color change to happen.

Moody Blues

For blue hues, use soil amendments like elemental sulfur and gypsum, or use an organic fertilizer containing cottonseed meal when feeding the plants. Recommendations to add aluminum sulfate to the soil, are often not necessary and could be harmful. Aluminum is plentiful and not an essential plant nutrient, and too much of it can be toxic.

Potting Soil Recipes

Potting soils for container plants are a mix of organic materials that generally do not contain garden soil. Just as not all plants will thrive in all types of garden soil, plants in containers have different soilless mixture needs.

Container gardens confine plant roots to a small amount of soil, limited by the container’s size, so the composition of the potting soil should be lightweight and free-draining. Plants will use soil nutrition and water quickly when they’re planted in a container, so it’s important to include particles that hold onto moisture and nutrients.

For seed-starting, create a mix with fine particles, moisture-holding ingredients, and sterile ingredients that won’t stimulate fungal or bacterial growth. Seed mixes don’t need fertilizer or nutrient mixes as the seed carries all the nutrition that the seedling needs to sprout. Once a plant develops its “true leaves,” it’s time to pot up the seedlings using a transplant mix, which will keep the plant growing strong until it’s ready for the garden. While seed-starting mix is soilless and sterile, once seedlings get growing they are going to need a boost of nutrients to keep them growing.

Like other potted plants and outdoor containers, houseplants dry out quickly and need a soil mix that can retain moisture and keep them hydrated. However, unlike outdoor containers, houseplants require sterile soil—anything else is likely to contain critters from the outdoors such as fungus gnats that may get into the house and can become a nuisance.

With the exception of compost, most soil ingredients do not have active biology. Prepare compost for indoor potting soil by baking moist soil in the sun or an oven for at least thirty minutes at 180°F (82°C). Alternatively, you can purchase sterilized compost. Store any leftover compost in an airtight container for future indoor and seed-starting potting mixes.

INGREDIENTS

SYMBOLS LEGEND

   Nutrients – contains nutrients

   Water – holds water in the soil for plant availability

   Drainage – allows water to flow freely

   Air – creates pockets of air in the soil

   Sterile – contains no soil microbes

   Acidic – acidic pH

   pH Neutral – neutral pH

   Byproduct – a waste product that can be repurposed into a potting mix ingredient.

KEY

Compost

Properly finished and screened compost is the cornerstone of building many potting soils. It is made up of broken-down organic matter that is rich in microorganisms and adds life to soil. Compost holds moisture and allows nutrients to be available to plants; however, quality varies greatly based on the inputs and composting methods.

Both urban and farm compost can be devoid of proper nutrients and contain undesirable materials such as pesticides, herbicides, and plastics. Use properly balanced homemade compost or purchase top-quality commercial compost from a trusted source.

Ground Bark / Bark Fines

Ground bark is byproduct of milling wood. It holds moisture and adds air space to potting mixes. As the bark slowly decomposes, it helps to improve the soil. Bark is sold as both a soil amendment and mulch, so it is available in various sizes. Use finely ground pine bark—also called “bark fines”—between one-quarter to one-half inch in size (.6 cm to 1.3 cm) for soil amending. It’s inexpensive and easy to acquire, but it is not recommended for root vegetables and seed mixes that require finer soil particles.

Sphagnum Peat Moss

Sphagnum peat moss is a naturally occurring, moisture-retaining material that is free of plant pathogens, weed seeds, mineral salts, or heavy metals. It aerates clay soil, binds sandy soil, and reduces nutrient leaching, which makes it a popular soil ingredient. Harvesting sphagnum peat moss comes with many sustainability issues that need to be considered (see the sidebar “Sphagnum Peat Moss and Environmental Responsibility”).

Sphagnum peat moss is acidic so it should be amended with one tablespoon (15 ml) garden lime per gallon (3.8 liter) to balance out the pH unless you are using it for acid-loving plants, such as blueberries and rhododendrons. When sphagnum peat moss dries, it can make the texture of potting soil stiff and impermeable, making it difficult to rehydrate. The acidic pH, rehydration issue, and sustainability concerns are strong reasons to go with a peat alternative in the home garden.

Coconut Coir

Coconut coir is made from the waste products of coconut husks. It has exceptional water-holding ability, is lightweight, and is often marketed a sustainable alternative to peat moss (see the sidebar “Sphagnum Peat Moss and Environmental Responsibility”). It has a neutral pH but doesn’t hold on to nutrients as well. There is a wide quality range in horticultural coconut coir products; some brands may not perform well in potting soil while others may be a valuable addition. Before making a large investment purchasing any coconut coir, test a few brands to find one that works for you.

Vermiculite

Vermiculite is a naturally occurring group of minerals that has a spongy texture when processed into pellets (chips). It absorbs and holds moisture and aerates the soil structure. Vermiculite has a neutral pH and it is often used in seed-starting mixes. Only horticultural grade vermiculite should be used for potting soils (see the sidebar “Safety”).

Rice Hulls

Rice hulls are a byproduct of rice farming. Hulls are the outer husks removed from each grain of rice after harvesting. They are heated and sterilized before being sold as a garden soil conditioner. Rice hulls are lightweight and break down quickly in the garden, usually within one season. They improve drainage, hold water in the soil, and improve aeration. Rice hulls are often inexpensive and can be found at homebrewing supply stores if you do not find them in a garden supply store.

Sand

Sand is fine granular rock that improves drainage when paired with organic materials. Too much sand in soil can affect the soil structure and decrease permeability. Adding sand to clay soils may seem like a good idea, but it’s better to add organic matter to adjust soil structure as sand and clay together will “cement” together and further decrease air space. Look for horticultural sand as a potting mix ingredient, as beach sand can contain salt, glass, and plastic.

Safety

Have you ever emptied a bag of soil mix just to be surrounded by a cloud of dust? Inhaling dust and particles can lead to health problems that can be easily avoided by using the proper safety equipment. I always recommend that you wear a mask and gardening gloves when mixing potting soils or using any bagged potting soil. Handling damp or wet soil can also reduce dust and particle inhalation, so add some water to your soil as you mix, fill pots, and plant.

Perlite

Perlite is a naturally occurring volcanic glass that is highly porous and lightweight. When heated, it puffs up and looks like balls of Styrofoam. It is added to soil to increase drainage and aeration, keeping soil lightweight and free-flowing. It is a good option for a succulent/cactus mix, propagating root cuttings, and container gardening.

Horticultural Pumice

Horticultural pumice, often just referred to as “pumice,” is a plentiful volcanic rock that can be added to soils to increase air space and improve drainage. Pumice is lightweight and does not hold water in the soil, so it is suitable for plants that require excellent drainage, such as succulents and cacti. It has similar properties to perlite, but it’s heavier, making it more suitable for small pots and tall plants that need more weight at their base for stability.

Sphagnum Peat Moss and Environmental Responsibility

Sphagnum peat moss comes from bogs, which make up 3 percent of the earth’s total surface. Peat bogs are part of the natural landscape of many countries around the world, with the largest area (approximately 25 percent) of peatlands in Canada. Peat bogs are excellent at absorbing and storing carbon to reduce climate change, and they are also home to many wildlife and plant species, some quite rare. Peat is used around the world as fuel for cooking and heating, and it is considered a slowly renewable fossil fuel that releases more emissions than coal and natural gas. Many countries have overharvested peatlands, which has resulted in protection and conservation efforts in countries throughout the globe.

Canada is the largest producer of Sphagnum peat moss as a soil conditioner. Canada contains 119 million hectares of peatlands and approximately 22,000 hectares are harvested for peat. Peatlands are protected in Canada and the producers must agree to regenerate the land that has been harvested. Even so, harvesting peat bogs releases carbon and displaces wildlife, which take many years to repair.

Coconut coir is promoted as a peat alternative, often being marketed as a “peat” product. There is some debate on whether it is truly more sustainable as the coir needs to be processed, which uses resources and can affect worker health, not to mention the long distances it will travel when shipped to temperate climates.

Many ingredients that are commonly used for home gardens and agriculture, while they are “organic,” “natural,” and good for building soil, raise sustainability questions and environmental considerations. It’s important not to simply replace what we harvest and sustain our natural systems but look to how they can be regenerated. Some materials are plentiful, but it takes a long time to replace them through natural growth cycles. Removing them may change the biodiversity and harm ecosystems. The supply of some materials is finite, and while plentiful now, once they are used, they cannot be renewed. The distance that materials travel, the processes used for packaging them, and the reduction of their functions in the natural landscape must all be considered with each material we bring into our garden. Investigate the supply chain before you buy to learn how the materials are sourced, harvested, and prepared to ensure they are in line with your values.

The best practice is to use what you have, glean waste, use byproducts, and acquire materials locally where possible. Just reducing the plastic bags that pre-mixed potting soils come in is progress. Buy local, in bulk, and build your own potting mixes to grow a wonderful garden to feed your body, wildlife, and the earth.

Recipes

Peat Moss Alternative

This recipe is made up of byproducts and therefore is a more eco-friendly alternative to peat. It is also pH neutral and doesn’t dry out like peat, making it a superior option for potting soil.

1 part compost

1 part coconut coir

1 part rice hulls or perlite

All-Purpose Soil Mix

Use this all-purpose soil mix in container gardens, raised beds, and for potting up seedlings. This recipe is useful if you have a variety of different potting mix needs.

2 parts screened compost

2 parts peat moss alternative

1 part perlite

1 cup (235 ml) worm castings per each gallon (3.8 L) of prepared mix

1 tablespoon (15 ml) greensand per each gallon (3.8 L) of prepared mix

1 tablespoon (15 ml) mineralized rock dust per each gallon (3.8 L) of prepared mix

1 tablespoon (15 ml) kelp meal per each gallon (3.8 L) of prepared mix

Acid-Loving Plant Mix

Blueberries, azaleas, and heathers will love this lower pH soil mix.

2 parts compost

1 part finely ground pine bark

1 part sand

1 tablespoon (15 ml) coffee grounds per each gallon (3.8 L) of prepared mix

Seed-Starting Mix

Seed-starting mix is sterile, offers balanced moisture retention and drainage, and has fine particles to allow seedlings to easily root.

2 parts screened and sterilized compost

2 parts peat moss alternative

1 part perlite

1 part vermiculite

Seedling Transplant Mix

A seedling transplant mix has excellent drainage and available nutrients for developing healthy roots on young plants and propagating cuttings.

2 parts screened compost

1 part peat moss alternative

1 part perlite

1/4 cup (60 ml) worm castings per each gallon (3.8 L) of prepared mix

Note: If the seedlings are moved to the garden in a few weeks after potting up, then this recipe is sufficient. But if you need to grow them in small pots for a longer period, they will need more nutrition. Bump the worm castings up to 1/2 cup (120 ml) per gallon (3.8 L) and apply an all-purpose liquid fertilizer every 2 weeks when watering.

Cacti and Succulent Mix

Succulents and cacti thrive in dry environments and require the soil to dry out completely between waterings. The best soil for them is made up of light, airy materials with excellent drainage.

1 part compost

1 part ground bark

1 part sand

1 part pumice

Basket Mix

This moisture-holding, nutritious, and lightweight soil mix is perfect for hanging baskets. Line hanging baskets with a coconut coir insert to further retain moisture.

2 parts compost

1 part perlite

1 part vermiculite

1 part worm castings

3 tablespoons (45 ml) blood or alfalfa meal per each gallon (3.8 L) of prepared mix

1 tablespoon (15 ml) kelp meal per each gallon (3.8 L) of prepared mix

Raised Bed Vegetable Mix

To produce the largest (and tastiest!) harvest possible, vegetable plants need lots of nutrients and humus-rich soil.

3 parts compost

1 perlite or rice hulls

1 part sand

1/4 cup (60 ml) worm castings per each gallon (3.8 L) of prepared mix

1 tablespoon (15 ml) greensand per each gallon (3.8 L) of prepared mix

1 tablespoon (15 ml) mineralized rock dust per each gallon (3.8 L) of prepared mix

1 tablespoon (15 ml) kelp meal per each gallon (3.8 L) of prepared mix

Woody Plants and Perennial Mix

Woody plants and perennials like a soil mix that breaks down slowly and balances moisture retention with good drainage.

2 parts compost

2 parts finely ground pine bark

1 part perlite or pumice

1 part sand

1 part mushroom manure (compost)

Indoor Plant Mix

Use this mix for indoor tropical plants. Ensure that the ingredients you use are sterile to avoid introducing plant pests and disease.

2 parts sterilized compost

2 parts peat moss alternative

1 part worm castings

1 part perlite

1 part vermiculite

1 part sand

Lawn Mix

After seeding your lawn, spread this mix over the seed or use it to fill in uneven spots.

2 parts finely screened compost

1 part sand

Epiphyte / Orchid Mix

Epiphytes such as orchids use potting soil as an anchor for their roots, so it should be loose, airy, and with excellent drainage.

4 parts finely ground pine bark

2 parts peat moss alternative

1 part perlite or pumice

Frugal Mix

Potting mix ingredients can add up to more than just great plants. Save a bundle by crafting your own potting mix out of ingredients that you have at home or can purchase inexpensively.

2 parts garden soil

2 parts homemade compost

1 part sand

1 cup (235 ml) rice hulls per each gallon (3.8 L) of prepared mix

1 cup (235 ml) dried, ground seaweed per each gallon (3.8 L) of prepared mix

Organic Mulches for Every Garden

Mulching is highly lauded as an essential part of soil insulation, deterring weeds, retaining soil moisture, and nourishing the soil. This wisdom comes straight from the forest. Plant materials such as leaves, bark, and seeds drop to the ground in forests and other wild spaces, where they create a carpet of plant material that decomposes to nourish and build up the soil below. In home gardens, we are taught to remove the plant debris that creates this carpet, and we are then left with bare soil around our plants that dries out quickly and invites weeds to take up residence. Mulching replaces this essential layer in the garden.

There are many different organic mulches that work well for various styles of gardens. Synthetic options like plastic, landscape fabric, and bark that has been dyed for aesthetics should be avoided. The inorganic nature of these materials is rife with problems that will ultimately harm soil, plants, and the ecology.

MULCH MATERIAL	DESCRIPTION	GOOD FOR	AVOID	NOTES
COMPOST	Properly finished and screened compost from the home garden or trusted commercial products. Compost as mulch will slowly leach beneficial nutrients and microbes into the soil through watering.	All gardens	Unfinished compost. Unknown source inputs. Some municipal waste-derived compost.	Homemade compost is free. Compost is readily available.

LEAF MOLD

Leaves are collected and shredded into mulch with a lawnmower or leaf blower on the mulch setting. Leaf mold breaks down quickly and has a high bacterial content.

Vegetables

Diseased or pest-infested leaves. Leaves sprayed with pesticides and herbicides.

Free. Readily available.

WOOD CHIPS

Wood chips from arborists or commercial sources make a great, all-purpose mulch for shrubs, trees, and perennial gardens that don’t need to be planted annually. Wood chips feed fungi, which is beneficial to long-term growers.

Perennials

Inexpensive. Readily available.

ROCKS

River stone, gravel, volcanic rock

Xeriscapes

Rock mulch under trees means leaves to pick out of the rocks.

Holds and radiates heat and cold.

PINE STRAW

Pine needles and pinecones make attractive and readily available mulch.

Woodland gardens

Does not affect soil pH as commonly rumored.

STRAW

Utilitarian mulch offering good winter protection.

Homesteads

Hay can contain weed seeds.

CARDBOARD

Shredded or torn cardboard pieces that protect soil from nutrient loss.

Rainy climates

Full sheets that can smother soil.

Slow to break down. Remove in dry seasons.

GRASS CLIPPINGS

Allow grass clippings to remain on the lawn as mulch.

Lawns

Grasscycling allows the grass to grow long and go to seed before cutting.

LIVING MULCH

Carpet gardening using low-growing groundcovers under and between plants.

Ornamental gardens

CHOP AND DROP

Drop plant material on the garden floor and allow it to naturally compost.

Regenerative gardens

Some plants can be specifically grown as mulch.

SNOW

Insulate garden beds with snow. A naturally occurring snowfall can provide winter insulation but is best combined with an all-weather mulch.

Cold climate gardens

Tender plants

AQUATIC PLANTS

Chop and drop fast-growing aquatic plants as mulch where they will not reseed or take root.

Dry land gardens

SEAWEED

Shredded seaweed as mulch for plants that naturally grow near oceans.

Coastal gardens

Adding too much seaweed causing plant salt injury.

SHEET MULCHING

Adding layers of carbon and nitrogen like paper, bark, leaves, and vegetation to compost in place.

Soil creation

Lasagna gardening and Hugelkultur methods for new soil creation.